LOCHINVAR GCF-40 1**

The registry does not print the 173 therms figure. This site computed it from the model's UEF, the ratio of hot water delivered to energy used, which the DOE CCD lists as 0.64. That UEF was combined with the DOE test's daily hot-water draw for the medium pattern, which DOE sets for a typical mid-sized household. The registry data was retrieved on 2026-09-19. The result describes energy use at the test's draw, not at your household's actual use. Your own daily draw may differ from the test, and the registry does not report by how much. The steps behind the figure are set out in how the annual cost is calculated.

Within its class, the model ranks 44th for lowest energy use among the 288 gas tank models at the medium draw pattern. Its gap of 12 therms below the 185 therms median places it among the lower-use models in that class. The first hour rating, the gallons of hot water available in the first hour from a full tank, is 70 gallons. The rated volume is 38 gallons. A household whose peak demand stays within 70 gallons matches the conditions this unit was tested under. Where peak demand regularly runs above that figure, the medium-pattern result does not describe the home. Units tested at other draw patterns can be compared in the selector by fuel, space and size.

This text states no running cost for the unit. The yearly cost of 173 therms depends on your state's average residential natural gas price, so the page computes it from your ZIP. Readers in different states will see different costs for the same 173 therms. The 12 therms gap to the class median converts into cost the same way, at your own rate. The cost calculator on your own ZIP applies that rate to this model's figure. The installed price range appears in its own block, with its source and date. It is a modeled installed-cost range, not a quote, and it does not change the energy figure of 173 therms.